Field of Invention
This invention relates to articles each comprising a sheet folded with a first set of concertina folds and so as to be transverse to these a second set of concertina folds. It also relates to improved apparatus and processes for producing such articles. Certain features or combinations of features of the apparatus and processes are thought to have independent value and the invention therefore extends to such features and combinations and to corresponding articles.
The present inventor has experimented to produce the first-mentioned articles with finishing of them, by attaching outer stiff portions to the folded sheet, being done by hand. In attempting to produce apparatus for carrying out this process and further steps of processing such articles, there have been encountered much inconsistency in production, very slow maximum speeds of production and various other snags.